Conically shaped air-oil separator

ABSTRACT

A liquid reservoir tank assembly includes a gas-liquid separator, such as an air-oil separator. A tank body has an open end, a portion of the tank body forming a liquid separation chamber, another portion of the tank body forming a liquid reservoir. A tank cover covers the open end of the tank body, the tank body and the tank cover providing a gas inlet and a gas outlet with a gas flow through the separation chamber from the gas inlet to the gas outlet. The gas-liquid separator is mounted in the separation chamber in the gas flow between the gas inlet and the gas outlet. The separator has a coalescing stage layer and a drain stage layer arranged radially symmetrically about an axis extending through the interior of the separator, the coalescing stage layer being upstream of the drain stage layer. Each of the layers is generally frustoconical in shape.

[0001] This application is a continuation of U.S. patent applicationSer. No. 10/282,334, filed on Oct. 28, 2002, issued as U.S. Pat. No.6,585,790 on Jul. 1, 2003, which is a continuation of U.S. patentapplication Ser. No. 09/623,095, filed on Oct. 20, 2000, issued as U.S.Pat. No. 6,485,535 on Nov. 26, 2002, which claims priority toInternational Patent Application No. PCT/US99/04392 filed on Mar. 1,1999.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates to filtering of liquids from gaseousstreams, and more particularly to air-oil separators such as those usedto remove suspended oil in compressor air discharge systems.

[0004] 2. Description of the Prior Art

[0005] Gas-liquid separators are used in various applications, but aremost notably used to separate oil from air. Air-oil separators aretypically used where it is necessary to remove suspended oil mist froman air stream, such as in the air discharge systems of air compressors,vacuum compressors and refrigerant compressors. The separator allows thedischarged air to be used without the contamination of the oil which hasentered the air in the compressor, and provides for the recovery of theoil so that it can be reused. The air-oil separator is typically mountedin a housing or tank having a separation chamber through which the airflows above an oil reservoir. The separator includes coalescing mediathrough which the discharge air passes while the oil is separated fromthe air flow. The coalescing media is cylindrically shaped and istypically mounted vertically, that is, in which the axis of thecylindrical coalescing media extends in a vertical direction. A shroudmay be provided within the separation chamber around the separator toslow the air flow and provide a vertical direction to the air flow as itencounters the separator. The contaminated air usually enters theseparation chamber from outside the air-oil separator and flows into thecenter of the separator where it then flows axially out of theseparation chamber. As the air flows radially through the layers of theseparator, the oil coalesces and collects in the interior of theseparator where it can be syphoned off or drained into the reservoir,typically by means of scavenging system, so that it can be reused. Theflow directions may also be reversed in which contaminated air isintroduced into the center of the air-oil separator and flows radiallyoutwardly through the separator with the oil coalescing and collectingon the outside of the separator where it drains into a reservoir. Anexample of a prior art air-oil separator is shown in U.S. Pat. No.4,878,929.

[0006] The characteristics of the air flow and the size of the separatorare limited by the cylindrical configuration of the separator. Forexample, where the air flows from the outside of the separator into theseparator and a shroud is used around the separator in the separationchamber, the air must flow through the narrow annular chamber betweenthe shroud and the outside of the separator before it enters theseparator. This annular chamber has a constant cross section, but theair volume decreases through this chamber since some of the air entersthe separator, and thus the air velocity decreases toward the top of theseparator. Since sufficient clearance must be provided between theshroud and the outside of the separator, particularly at the bottom ofthis annular chamber, the size of the separator, and thus the effectivesurface area provided by the separator, is limited by the size of theshroud.

SUMMARY OF THE INVENTION

[0007] The present invention provides advantages over the prior artdesigns of air-oil separators that have not been realized heretofore.The present invention provides an air-oil separator which is generallyconically shaped, providing a greater effective surface area over thesame axial length than the prior art cylindrically shaped separators,since the generally conically shaped separator can be made with a largerdiameter at the upper end while still providing sufficient clearancefrom the shroud at the lower end.

[0008] The air-oil separator of the present invention also provides afunnel type action to direct the flow of scavenged oil into a pool orreservoir where the oil can be more easily collected. This feature maybe particularly advantageous when the separator is mounted in ahorizontal orientation, that is, in which the axis of the separatorextends horizontally. In this configuration, the prior art cylindricalseparator collected oil along the bottom portion of the separator, and,since the separator extended horizontally, the oil tended to accumulatein this portion of the separator and not readily to drain off. Becausethe generally conically shaped separator of the present invention has asloped bottom surface when mounted horizontally, the oil more readilydrains from the separator and does not tend to collect in the bottomportion of the separator and inhibit separator performance. As a result,the separator has a longer life because it is not contaminated withaccumulated oil.

[0009] The generally conically shaped air-oil separators of the presentinvention may be used in existing oil reservoir tank designs, thuseliminating the need for modification. They may also be used in aninventive new oil tank design which utilizes the advantages of thegenerally conically shaped separators.

[0010] These and other advantages are provided by the present inventionof a liquid reservoir tank including a gas-liquid separator, comprisinga tank body having an open end, a portion of the tank body forming aliquid separation chamber, another portion of the tank body forming aliquid reservoir; a tank cover covering the open end of the tank body,the tank body and the tank cover providing a gas inlet and a gas outletwith a gas flow through the separation chamber from the gas inlet to thegas outlet; and a gas-liquid separator mounted in the separation chamberin the gas flow between the gas inlet and the gas outlet; the separatorcomprising a coalescing stage layer and a drain stage layer arrangedradially symmetrically about an axis extending through the interior ofthe separator, one of the layers positioned within the other of thelayers, the coalescing stage layer being upstream of the drain stagelayer, each of the layers being generally frustoconical in shape wherebyboth of the layers are closer to the axis at one end that at the otherend.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is a top plan view of an oil reservoir tank assembly withan air-oil separator according to the present invention.

[0012]FIG. 2 is a side sectional view of the oil reservoir tank assemblytaken along line 2-2 of FIG. 1.

[0013]FIG. 3 is a detailed side sectional view of a portion of theair-oil separator of FIG. 2.

[0014]FIG. 4 is a top plan view of another oil reservoir tank assemblywith an air-oil separator according to another embodiment of the presentinvention.

[0015]FIG. 5 is a side sectional view taken along line 5-5 of FIG. 4

[0016]FIG. 6 is an end sectional view taken along line 6-6 of FIG. 5

[0017]FIG. 7 is a detailed side sectional view of a portion of theair-oil separator of FIG. 5.

[0018]FIG. 8 is an end elevational view of yet another oil reservoirtank assembly with an air-oil separator according to another embodimentof the present invention.

[0019]FIG. 9 is a side sectional view taken along line 9-9 of FIG. 8.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0020] Referring more particularly to the drawings and initially toFIGS. 1 and 2, there is shown an oil tank assembly 10 according to thepresent invention. The tank assembly shown and described herein is onlyone of many arrangements in which the present invention may be used, andthe tank and separation configuration may be altered significantlywithout affecting the present invention. The tank assembly 10 comprisesa body 11 having a reservoir 12 formed at the bottom for collection ofoil removed by in the oil separation process. The upper portion of thebody 11 forms a separation chamber 13. The top of the separation chamber13 is enclosed by a tank cover 14 which is attached to the body 11 by aplurality of bolts 15 or other suitable fastening devices. A tank sealor gasket 16 is proved around the upper rim of the body 11, between thebody and the tank cover. Preferably, the tank seal 16 comprises ano-ring provided in a corresponding groove in the bottom of the tankcover 14 and another o-ring provided in a corresponding groove on thetop of the upper rim of the tank body 11. An air inlet 17 is provided onone side of the body 11 for air to enter the separation chamber 13. Theair flows from the separation chamber through a passage (not shown) inthe tank cover 14 and through an air outlet 18 provided in a tank cover.

[0021] Within the separation chamber 13 is a generally cylindricalshroud 20 which diverts the incoming air flow from the air inlet 17 andcauses the air to flow down and around the shroud. This provides a firststage air-oil separation, in that, large droplets of oil are separatedby the abrupt change in air flow and these oil droplets fall into thereservoir 12. A safety valve 19 is also provided in the body 11extending through the shroud 20. The safety valve 19 is a pressurerelief valve which opens in the event that air pressure inside theshroud 20 increases above a predetermined level. The air flow thenpasses upwardly and axially inwardly, through an air-oil separator 21comprising two generally conically shaped or generally frusto-conicallyshaped layers 22 and 23.

[0022] The upstream layer 22 is a coalescing stage layer. The downstreamlayer 23 is a drain stage layer. In the embodiment shown in FIG. 2 inwhich the flow of air is from the outside to the inside of the air-oilseparator 21, the coalescing stage layer 22 is on the outside of thedrain stage layer 23, and the drain stage layer is inside the coalescingstage layer. The layers 22 and 23 are each preferably made of a moldedor formed media so that they can be readily shaped into the desiredconical or frusto-conical configuration. A pleated or wrapped media mayalso be used. The layers are comprised of any suitable combination ofmaterials used in air-oil separation, such as fiberglass, polyester,polypropylene or metal, some of which may be pleated in a conventionalmanner, or which may be molded, formed, wrapped or otherwise shaped. Asshown in FIG. 3, the air-oil separator also preferably includes an outerwrap layer 25 on the exterior of the separator, and a support member 26along the interior surface of the layer 23.

[0023] The layers 22 and 23, along with the layers 25 and 26, areassembled into an air-oil separator unit 21 which is mounted in theseparation chamber 13 within the shroud 20. The lower ends of each ofthe layers 22, 23, 25 and 26 are set in a hardenable sealing material,such as urethane, epoxy or plastisol, which is molded in place in agenerally circular, lower connection plate 24. The lower ends of thelayers 22, 23, 25 and 26 are thus sealed to the lower connection plate24, and fluid is prevented from flowing into or out of the interior ofthe separator, except through the layers. Alternatively, in place of themetal connection plate 24, the bottom ends of the layers 22, 23, 25 and26 can be inserted into a plastic end cap made of a moldable plastic orelastic material such as polyurethane, which is molded in place; such abottom end cap seals and holds the layers in position without asupporting metal connection plate. The upper ends of the layers 22, 23,25 and 26 are set in a similar hardenable sealing material molded in anupper mounting plate assembly 27, a portion of which extends radiallyoutwardly from the layers. As shown in FIG. 3, the assembly 27 comprisesan inverted trough portion 28 which surrounds the hardenable material inwhich the ends upper ends of the layers 22, 23, 25 and 26 are set, and aflange portion 29 which extends between the upper rim of the body 11 andthe tank cover 14 and is secured in place by the connection of the tankcover on the tank body. The portions 28 and 29 are attached together,such as by welding. The upper ends of the layers 22, 23, 25 and 26 arethus sealed to the upper mounting plate 27, and fluid is prevented fromflowing into or out of the interior of the separator, except through thelayers. Alternatively, in place of the upper mounting plate assembly 27,an integrated upper end cap and flange may be formed in accordance withthe disclosure of U.S. patent application Ser. Nos. 09/174,137 and09/174,139, now U.S. Pat. Nos. 6,136,076 and 6,093,231, respectively,the disclosures of which are hereby incorporated by reference in theirentireties.

[0024] A scavenging tube 30 extends downwardly from the tank cover 14into the separation chamber inside the drain stage layer 23. Oildraining from the layer 23 can be withdrawn therefrom using the draintube 30.

[0025] Unlike the general cylindrical air-oil separators of the priorart, the layers 22 and 23 of this invention are generally conicallyshaped, or frusto-conically shaped, providing a larger amount of activesurface area per axial length of the separator element, and providing afunnel type shape into which the scavenged oil may flow to be withdrawnthrough the tube 30 using a conventional oil scavenging system.

[0026] The tank assembly 10 shown in FIGS. 1-3 is designed to allow theincorporation of the generally conically shaped air-oil separators in anotherwise conventionally designed air-oil separator. The uniquely shapedseparators may also be incorporated into a tank assembly designedspecifically for their use, and such a tank assembly 110 is shown inFIGS. 4-7. The tank assembly 110 has a body 111, a reservoir 112, aseparation chamber 113, a tank cover 114, tank cover bolts 115, a tankseal 116, an air inlet 117, an air outlet 118, a safety valve 119, ashroud 120, and an air-oil separator 121 comprising a coalescing stagelayer 122 and a drain stage layer 123, each of which is generallysimilar to the body 11, the reservoir 12, the separation chamber 13, thetank cover 14, the tank cover bolts 15, the tank seal 16, the air inlet17, the air outlet 18, the safety valve 19, the shroud 20, the air-oilseparator 21, the coalescing stage layer 22 and the drain stage layer 23already described.

[0027] Unlike the layers 22 and 23 of FIGS. 2 and 3, the coalescingstage layer 122 and the drain stage layer 123 are each made as separatemodules which can be individually removed. Each of the elements 122 and123 is mounted at each end in integrated seals which can be made ofurethane or any suitable material. Unlike the air-oil separator 21 ofFIGS. 1-3, the air-oil separator is not assembled into an integratedunit. Instead, each of the elements 122 and 123 is separate and can beindividually replaced as needed. The drain stage element 123 is selfsupporting. The coalescing stage element 122 is mounted in a frame thebottom of which is attached to a scavenge flow drain tube 130 whichextends through the reservoir 112. At the bottom of the tube 130 is ascavenged oil return port 132.

[0028] While the air-oil separator of this invention has been describedwith reference to an oil tank having an outside-in air flow, that is, inwhich the air flows radially from outside the separator to the interiorof the separator, it should be understood that the separator providesequal advantages when the air is flowing the opposite direction. Insteadof air entering the oil tank assembly 10 through the inlet 17 andexiting through the outlet 18, the air flow may be reversed with the airentering the oil tank through the passage 18 and exiting through thepassage 17. The air-oil separator provides the same advantages underthese circumstances. Likewise, while the air-oil separator of thisinvention has been described with reference to a separator which ismounted vertically in an oil tank assembly, that is in which the axis ofthe separator extends vertically, the advantages of the separator ofthis invention can also be realized in configurations in which theseparator is mounted horizontally.

[0029]FIGS. 8 and 9 shows a tank assembly 210 which incorporates bothinside-out air flow and a horizontally mounted air-oil separator. Thetank assembly 210 has a body 211, a reservoir 212, a separation chamber213, a tank cover 214, tank cover bolts 215, a tank seal 216, a shroud220, and an air-oil separator 221 comprising a drain stage layer 223 anda coalescing stage layer 222, each of which is generally similar to thebody 11, the reservoir 12, the separation chamber 13, the tank cover 14,the tank cover bolts 15, the tank seal 16, the shroud 20, the drainstage layer 23 and the coalescing stage layer 22 already described.

[0030] Unlike the previously described embodiments of the invention, theseparator of FIGS. 8 and 9 uses an inside-out flow, with an air inlet217 is provided in the tank cover 214 and an air outlet 218 is providedin the tank body 211 on top of the tank. Therefore, the coalescing stagelayer 222 of the separator is provided inside the drain stage layer 223,and the oil drains from the separator into the reservoir 212. Since thegenerally conically shaped air-oil separator 221 of this embodiment doesnot have layers which extend completely horizontally, oil does not tendto accumulate along the bottom of the separator. Instead, the slopedconfiguration of the bottom of the separator facilitates the drainage ofthe oil from the separator so that it falls more readily into thereservoir 212.

[0031] While the layers of the air-oil separator of this invention havebeen described as being generally conical or generally frusto-conical,this is intended to include layers which have pleats or soft pleats orribs, and thus do not have smooth inner or outer surfaces. It iscontemplated that layers having such pleats or ribs which are thengenerally formed into a conical or frusto-conical shape, rather than acylindrical shape, would realize the advantages of the presentinvention.

[0032] Other variations and modifications of the specific embodimentherein shown and described will be apparent to those skilled in the art,all within the intended spirit and scope of the invention. While theinvention has been shown and described with respect to particularembodiments thereof, these are for the purpose of illustration ratherthan limitation. Accordingly, the patent is not to be limited in scopeand effect to the specific embodiments herein shown and described nor inany other way that is is inconsistent with the extent to which theprogress in the art has been advanced by the invention.

What is claimed is:
 1. A gas-liquid separator for mounting in a tankassembly; the separator comprising: (a) a mounting plate assemblyincluding a flange portion and an inverted trough portion; (i) theflange portion and inverted trough portion being separated from oneanother, in the mounting plate, by turns in the mounting plate; (ii) theflange portion being positioned non-coplanar with the inverted troughportion; (b) an upstream coalescing stage having a funnel shape with:(i) a wide end secured to the inverted trough portion of the mountingplate; and, (ii) a narrow end remote from the wide end; and, (c) adownstream drain stage surrounded by the coalescing stage layer andsecured to the inverted trough portion of the mounting plate.
 2. Agas-liquid separator according to claim 1 wherein: (a) the coalescingstage is selected from fiberglass, polyester and polypropylene.
 3. Agas-liquid separator according to claim 2 wherein: (a) the drain stageis selected from fiberglass, polyester and polypropylene.
 4. Agas-liquid separator according to claim 3 wherein: (a) the drain stagehas a funnel shape with: (i) a wide end secured to the mounting plate;and, (ii) a narrow end remote from the mounting plate.
 5. A gas-liquidseparator according to claim 4 wherein: (a) each one of the coalescingstage and drain stage is frusto-conical.
 6. A gas-liquid separatoraccording to claim 1 including: (a) an interior support membersurrounded by the drain stage layer.
 7. A gas-liquid separator accordingto claim 3 wherein: (a) the coalescing stage layer is molded or formedmedia.
 8. A gas-liquid separator according to claim 7 wherein: (a) themounting plate assembly comprises metal.
 9. A method of mounting agas-liquid separator in a tank assembly; the method comprising steps of:(a) mounting a drain stage element over an air outlet in a tankassembly; (i) the drain stage element having a wide end secured to anopen end cap and a narrow end remote from the wide end; (ii) the drainstage element being mounted with the wide end over the air outlet; and,(b) after the step of mounting a drain stage element, separatelymounting a coalescing stage element over and adjacent the drain stageelement; (i) the coalescing stage element having a funnel shape with awide end secured to an open end cap; (ii) the coalescing stage elementbeing mounted with the wide end over and adjacent the air flow outlet.10. A method according to claim 9 wherein: (a) the step of mounting adrain stage element comprises mounting a drain stage element having afrusto-conical shape.
 11. A method according to claim 9 wherein: (a) thestep of mounting a coalescing stage element comprises mounting acoalescing stage element having a frusto-conical shape.
 12. A methodaccording to claim 9 wherein: (a) the step of mounting a coalescingstage element comprises mounting a coalescing stage element having acoalescing stage selected from fiberglass, polyester and polypropylene.13. A method according to claim 12 wherein: (a) the step of mounting adrain stage element comprises mounting a drain stage element having adrain stage selected from fiberglass, polyester and polypropylene.
 14. Amethod of servicing a gas-liquid separator mounted in a tank assembly;the method including a step of: (a) dismounting a first coalescing stageelement having a wide end and a narrow end, from a position over a drainstage element, without dismounting the drain stage element.